Help with AFM Issue?

[EuroDat]

I bought the volume knob at Radio Shack, $3.95, solder it to about 6 feet of speaker wire on one end and put the appropriate "butt"? connectors on the other end.  Ran the wire through the firewall, plugging it into the wires behind the thermostat.  The adjustable knob inside with me, drove it for a month adjusting little bits at a time until it was perfect (to me).

 

Before I did it, it would cough spit and sputter until 2,500 RPM then pull like normal.  Now it'll paint black marks out of my driveway, with a little clutch work. 

Hey Site, We must of been twins in another life😂

Mine is now tucked under the dash because I haven't got around to moving it back to the engine manifold.

[siteunseen]

Great minds...... 

 

Read Fastwomans nice permanent solution, post #66.  One of these days maybe my life will slow down and I can do it to mine.

 

http://www.classiczcars.com/topic/37549-purs-like-a-kitten/page-4

[EuroDat]

I remember Sarah doing something nifty with the ecu harness. Thanks for posting that link. I would love to find enough time to do that as well.

Too many other projects on my bucket list.

[hr369]

These cure all efi problems.

 

[siteunseen]

Somebody said something I've not heard before the other day, FUEL INFECTION

That's pretty good.

[SilverSurfer]

Alright, I've got a photo of one of the spark plugs:

 

 

A few things to consider:

 

- I pulled three and all three are the same. So, I am assuming the other three are the same.

- Please remember I was running the previous AFM for some time (about 6 months) before replacing it with the "new" one (only about 10 miles on this one)

 

Because the car, with the new AFM behaved like it was running a bit lean, I adjusted the Idle Mixture Adjustment Screw about a quarter turn toward rich (clockwise). I'd read that it only adjusts the mixture at idle (and, thus, the name), but the car is running really well now, both in idle and when running. It has a lot of power, too (contrary to previously). However, I did go through everything and make sure the connectors were firmly connected and that both ends were tight (where the tubes for the air filter and the other end connect). I took her out on the road, city and highway, and she was running smoothly at all speeds.

In any case, I will drive it for a while, see if it acts up again, and monitor the gas mileage.

[EuroDat]

Good to hear its running ok again. The idle adjustment screw shouldn't have much effect above idle.

If you played with all the connectors, it could be a loose or dirty connector. Bad connectors can really mess things up in these old efi systems.

Here is an article about cleaning the connectors. Always good to check it just in case.

http://atlanticz.ca/zclub/techtips/electricalconnections/index.html

[rcb280z]

You would be surprised just how much the idle adjustment screw changes how it runs "at idle". A friend of mine "smog tech" adjusted mine on his dyno and I was amazed at just how much he was able to adjust the idle mixture with the idle screw.

 

Like Chas said "you wont see any results from the idle adjustment screw above idle". 

Edited October 30, 2015 by rcb280z

[TomoHawk]

Can you get or rent a sniffer from somewhere? Adjusting by 'feel' is in no way an accurate thing.

[rcb280z]

Can you get or rent a sniffer from somewhere? Adjusting by 'feel' is in no way an accurate thing.

Yep, thats right. The best way is on a dyno with a "sniffer" hooked up to it IMHO.  You can see what condition your motor and fuel system are in. I had my 77 done this way after installing a rebuilt  MSA afm. BTW,they truly are rebuilt on original cores. I was surprised. But it needed a slight tweak which it got on the dyno. She's running good and burning clean.

Edited October 30, 2015 by rcb280z

[TomoHawk]

Maybe they hany dynamometer shops on every corner in California, but there aren't any in Ohio.

[rcb280z]

Wish I owned one. I'd have fun